Media content providers and creators are always seeking ways to better engage and attract viewers of media content. For example, various mobile applications have been developed that allow a user to watch a media content instance (e.g., a television program or a broadcast of a live event) on a television or other suitable display device, and, at the same time, access additional content associated with the media content instance by way of a mobile device (e.g., a mobile phone or tablet computer). However, current interactive applications leave room for improvement. For example, it would be desirable for a user to be able to more effectively and enjoyably use his or her mobile device to interact with a media content instance (e.g., a live event) being displayed by a display device (e.g., a television). To illustrate, it would be desirable for a user to be able to aim a sensor (e.g., a camera) of the mobile device at a display device and view augmented reality content associated with the live event within a display screen of the mobile device. However, numerous technical challenges have heretofore prevented this type of user interaction with a media content instance that is being displayed by the display device.